Dark red blood in sputum in the early morning may be caused by lung infection, pharyngitis, lung cancer, tuberculosis, bleeding gums and so on. 1. Lung infection is the more common cause, due to the damage of the infection to the mucous membrane of the trachea and bronchial tubes, resulting in bleeding, thus showing blood in the sputum in the early morning. 2. Pharyngolaryngitis, bleeding in the throat area due to the stimulation of infection, can also appear similarly. 3. Lung cancer, bleeding from tumor is a common cause, after bleeding, the blood is coughed out with sputum, which is manifested as blood in sputum. 4. Tuberculosis, hemoptysis is a typical manifestation of tuberculosis, but it can be accompanied by night sweating, chest pain and other manifestations. 5. Gum bleeding, bleeding gums can not be discharged in time during sleep, and will be discharged with sputum in the morning. Blood in the sputum need to consult a doctor in time, under the guidance of the doctor for examination to clarify the cause of the disease, timely treatment.